Jan 02, 2016  · Sound waves are longitudinal and travel in the same direction in which they are propagated, so denser, less compressible materials will propagate the forward wave faster. #4 JoeCaputo , Jan 1, 2016 Lawper In 3D At the time, people believed that light waves, just as sound waves. of the OPERA experiment does pan out, the implications are much more mind-bending. Under special relativity, if something travels. Actually…